Electrical printing methods and apparatus for decorating cylindrical articles



12 .1959 w. E. JOHNSON 3,460, 68

ELECTRICAL PRINTING METHODS AND APPARATUS FOR nnconwme CYLINDRICALARTICLES Filed Feb. 24. 1965 3 Sheets-Sheet 1 -u m M E18 INVEN QRMu/nqiJ/rgjod Aug. 12, 1969 FOR DECORATING CYLINDRICAL ARTICLES FiledFeb. 24. 1965 w. E. JOHNSON 3,460,468 ELECTRICAL PRINTING METHODS ANDAPPARATUS I5 Sheets-Sheet 2 I no I [172] 1 72w II! II III I II Aug. 12,

ELECTRICAL PRINTING METHODS AND APPARATUS w. E. JOHNSON FOR DECORATINGCYLINDRICAL ARTICLES Filed Feb. 24 1965 Cd r11 5 Sheets-Sheet 5 p 2 45 I[I] 2 31R flrroRNEKS United States Patent 3,460,468 ELECTRICAL PRINTINGMETHODS AND AP- PARATUS FOR DECORATING CYLINDRI- CAL ARTICLES William E.Johnson, Temperance, Mich., assignor to Owens-Illinois, Inc., acorporation of Ohio Filed Feb. 24, 1965, Ser. No. 434,819

Int. Cl. B41f 17/22; B411 13/02; G03g 15/00 US. Cl. 10140 11 ClaimsABSTRACT OF THE DISCLOSURE Electrical printing methods and apparatus fordecorating cylindrical articles such as bottles, tumblers and the like.Printing powder particles are electrically transferred directly from afiat surfaced source such as a powder bed through a flat stencil screento the curved article surface. Relative motion between the article, bedand stencil is established so that the article is rolled laterallyacross the image area of the stencil at a umform distance from thestencil to scan the image. Powder particles being transferred from thebed to the article surface are confined by a slotted plate to arelatlvely narrow band encompassing a plane normal to the bed surfaceand passing through the axis of relative rotation of the article.

In my prior application Ser. No. 393,817, filed Aug. 31, 1964, nowabandoned, refiled as a continuation-in-part, and issued as Patent No.3,402,659, there is disclosed certain methods and apparatus forelectrically transferring printing powder particles from a powder supplythrough a stencil screen to the surface of a flat article. As disclosedin Patent No. 3,402,659 the powder s disposed in a loosely packed layerbeneath a stencil screen formed with an image shaped aperture, and thearticle to be printed is brought into vertical registry above thescreen. Electric potential pulses are applied to electrically charge thepowder particles in the supply and to establish an electric fieldoriented to electrically attract particles from the supply through theimage aperture of the screen to the article surface. In thisarrangement, the entire image is transferred at one time and, because ofthe parallel uniformly spaced relationships between the article surface,stencil screen and powder bed surface, an image of uniform density isapplied to the flat article.

In many instances, it is desirable to decorate art1c-les which are notfiat, one common example being repreented by glass bottles or tumblersin which the surface to be decorated is of a generally cylindricalshape. Typically, as in the case of printing a label directly upon thesurface of a glass bottle, such decorating operations involve thedecorating of large quantities of articles on a mass production basis.Where the article being decorated is a glass article, it is desirablethat the article be electrically conductive. This may be accomplished byapplying an electrically conductive coating to the article, but in theusual case the article is heated to a relatively high temperature duringthe decorating operation. From a practical standpoint it is advantageousto apply the decoration to the glass bottle while the bottle is stillresidually heated from the bottle forming operation. Thus, for its mostpractical application, an electrical printing process for decorating hotglass bottles should be capable of a production rate which can bematched to the relatively high output of a glass bottle forming machine.

Presently available processes for electrically applying printing powderimages to curved article surfaces on a production line scale are almostentirely restricted to various types of offset decorating processes. Ina 3,460,468 Patented Aug. 12, 1969 er: I

typical offset process, the printing powder image is electricallytransferred from a powder supply bed through a stencil screen to a flatoffset plate to form an image shaped layer of powder particles on thesurface of the plate. The image is then transferred from the plate tothe article surf-ace by rolling the article surface laterally across theimage on the plate. While offset processes can be performed at highproduction rates, it isnecessary to provide complex mechanism forconditioning or manipulating the plates into and out of relationshipwith the powder supply and with the article being decorated.

While various processes for applying a powder image directly to acylindrical or conical article surface from a powder supply bed througha stencil screen have been developed, in the usual case these directprinting processes require preparation or reconditioning of the powderbed in Ways such that these processes are not well adapted to highproduction rates.

Accordingly, it is an object of the present invention to provide methodsand apparatus for decorating curved article surfaces by electricallytransferring printing powder particles directly from a source through astencil screen to the articles at a high rate of production.

It is another object of the present invention to provide methods andapparatus for applying image-shaped layers of printing powder particlesdirectly to curved article surfaces which do not require preparation orreconditioning of the powder bed in a manner which limits the productionrate.

It is another obiect of the present invention to provide methods andapparatus for transferring printing powder particles from a flat powderbed through a stencil screen directly to a curved article surface whichresults in a clear and sharply defined image on the article.

The foregoing and other objects are achieved by depositing a bed ofprinting powder particles in a layer of uniform thickness upon a fiatsupporting surface such as a conveyor belt or reciprocating plate. Asemi or nonconductive plate is located in a horizontal positionimmediately above the powder bed. The plate is formed with an elongate,relatively narrow slit which extends entirely across the width of thepowder bed. A fiat stencil screen having an image defining aperture islocated immediately above the plate and the article being decorated isbrought into a decorating position in spaced relationship above thescreen with the axis of the curved surface of the article disposed in ahorizontal position in parallel vertical registry with the slit in theplate. The article is supported for rotation about its axis. In the caseof articles of noncircular cross section, for example a bottle ofelliptical cross section, the axis of rotation may be supported forcyclic movement to compensate for the surface configuration.

During the decorating operation, an electric field is established whichelectrically charges powder particles in the bed and is oriented toattract the charged particles upwardly through the slit in the plate andthe image aperture of the screen to the article surface. The screen andslitted plate are supported for horizontal movement relative to eachother in a direction perpendicular to the longitudinal extent of theslit. At the beginning of the decorating operation, the slit is locatedat one edge of the image aperture, and during the decorating operationthe screen and plate are moved relative to each other so that the slitis traversed entirely across the image aperture in a scanning typerelationship. During relative movement between the screen and slittedplate, the powder bed and screen are maintained against horizontalmovement relative to each other and the bottle axis is maintained invertical registry with the slit in the plate. During the hor- 3 izontalrelative movement between the screen and the plate, the bottle isrotated, as by contacting its surface with a rail ion the screen so thatthe bottle rolls with its periphery moving at the same velocity as thehorizontal movement of the screen relative to the bottle axis.

The electric field is established by connecting the bottle sunfiace toan electric potential source and by connecting a second electricpotential source of opposite polarity to an electrically conductivemember located beneath the powder bed. In all cases, the electric fieldis such that only powder particles in the bed in or close to verticalregistry with the slit are electrically charged. In one case, this maybe accomplished by forming the electrically conductive member as anelongate relatively narrow member located in vertical registry with theslit in the plate. In this case, the conductive member is maintained inregistry with the slit throughout the decorating operation.Alternatively, an electrically conductive plate of dimension such as toentirely underlie the slitted plate may be employed. In this case, theslitted plate is of a material having substantially the same electricalresistivity characteristics as the powder of the bed. The slitted plateis placed in contact with the upper surface of the powder bed, and thoseparticles not in registry with the slit do not become charged, butinstead act as merely a series resistance between the conductive plateand the slitted plate.

Other objects and features of the invention will become apparent byreference to the specification and to the drawings.

In the drawings:

FIGURE 1 is a schematic side elevational view, partially in crosssection of one embodiment of the invention;

FIGURE 2 is a schematic side elevational view, partially in crosssection of a second embodiment of the invention;

FIGURE 3 is a schematic side elevational view, partially in section of athird embodiment of the invention;

FIGURE 4 is a detailed cross sectional view taken upon line 4-4 ofFIGURE 3',

FIGURE 5 is a schematic side elevational view, partially in crosssection, of still another embodiment of the invention.

FIGURE 6 is a schematic diagram of an electric control circuit;

FIGURE 7 is a schematic diagram of a pneumatic motor control circuit;

FIGURE 8 is a schematic diagram of a second form of electric controlcircuit; and

FIGURE 9 is a schematic diagram of a third form of electric controlcircuit.

In FIGURE 1, there is disclosed schematically one form of the inventionin which an endless conveyor belt 10 of relatively thin rubber,neoprene, or a semi-conductive material which is operatively trainedaround a pair of end rolls 12 and 14 rotatably supported by conventionalframe structure (not shown). The electrical conductivity characteristicsof the belt should be in the same range of conductivity as that of thepowder. End roll 12 is driven by conventional drive means M1 so that theupper run 16 of belt 10 moves from left to right as viewed in FIGURE 1.

A supply of printing powder particles 18 is dispensed onto upper run 16of the belt near its upstream end from a schematically illustratedsupply hopper 20, the rate at which powder is dispensed from hopper 20being controlled in accordance with the rate of movement of the belt byconventional means, not shown. At spaced locations along upper run 16, apair of stationary frame members 22 and 24 extend transversely acrossand above upper run 16. The left hand frame member 22 as viewed inFIGURE 1 functions as a doctor blade to smooth and level the surface ofpowder particles 18 on upper run 16 to form a bed or layer of uniformthickness upon the belt as the particles are carried downstream beyondframe member 22.

Frame members 22 and 24 serve to support a fiat horizontally disposedplate 26 of an electrically non-conductive material in spacedrelationship above the surface of the powder bed upon run 16 of thebelt. A stencil screen 28 is mounted within a rectangular framedesignated generally 30 which is supported upon the upper surface ofplate 26 for horizontal movement in the direction indicated by the arrowA of FIGURE 1.

Preferably, stencil screen 28 takes the form of a relatively fine wiremesh which is coated in a fashion such that the coating fills theopenings in the mesh. The coating material is chosen so that it can beremoved from selected areas of the screen by a photographic process tothereby form an image defining aperture through the screen. Suitablematerials and processes for preparation of a screen of this type aredisclosed in United States Patent No. 3,100,150. The image aperture isschematically illustrated at 32. Screen 28 may be shifted horizontallyin either direction parallel to the direction of movement of belt 10 bysuitable means such as a pneumatic motor 34 having its piston rod 36coupled to screen frame 30.

In the apparatus from FIGURE 1, the article being decorated may take theform of a cylindrical bottle B supported from suitable conveying meansdesignated generally 38 as by a support yoke 40 which supports thebottle for free rotation about the axis of its cylindrical surface. Thisaxis R is horizontally disposed during the decorating operation andextends in a direction perpendicular to the direction of movement ofbelt 10.

Conveyor 38 is driven, as by drive means M2, to convey bottles B whichare to be printed into the position shown in FIGURE 1. When the bottleis in the decorating position shown in FIGURE 1, the axis R about whichthe bottle is supported for rotation is disposed in parallel verticalregistry with a relatively narrow elongate s-lit 42 cut through plate26. A limit switch LS1 is located to be engaged by support yoke 40 whenthe bottle is in the decorating position. Slit 42 is likewise inparallel vertical registry with a relatively narrow elongateelectrically conductive member 44 which extends transversely beneathupper run 16 of belt 10. In FIGURE 1, slit 42 and conductive member 44are shown in transverse cross section, the longitudinal extent of theslit and conductive member extending in a direction perpendicular to thepaper. The longitudinal extent of slit 42 and conductive member 44 isgreater than the corresponding maximum dimension of the image definingaperture 32 of stencil screen 28.

Conductive member 44 is electrically connected to one terminal of a highvoltage source V1 while bottle B is electrically connected, as via abrush assembly schematically illustrated at 46 to one terminal of asecond high voltage power supply V2. The opposite terminals of voltagesources V1 and V2, as well as screen 28, are connected to an electricalground. For further details of the characteristics of voltage sources V1and V2 and their operation, reference may be had to Patent No.3,402,659.

In addition to the structure set forth above, a pair of limit switchesLS2 and LS3 are mounted to be engaged by screen frame 30 when the screenframe is at its respective right or left-hand limits of travel as viewedin FIG- URE 1.

An exemplary control arrangement for the FIGURE 1 embodiment isdisclosed in FIGURES 6 and 7. As indicated in FIGURE 7, a conventionalpneumatic circuit employing a solenoid actuated 'four way reversingvalve is used to control pneumatic motor 34. The circuit includes apressure source P connected through the four-way reversing valve V tomotor 34 via a rod-end conduit 48 and a head-end conduit 50. The valvecontrol solenoids are designated 34E and MR, the connections in thevalve being set up so that piston rod 36 is retracted when controlsolenoid 34R is energized, as indicated in FIGURE 7, the connectionsbeing reversed to extend the piston rod when solenoid 34E is energized.

The electrical control circuit is shown in FIGURE 6, and its operationmay be best described in terms of operation of the apparatus ofFIGURE 1. As an initial condition, it will he assumed that conveyor isstationary with a supply of powder supported upon upper run 16 of thebelt, that screen frame 30 is at its extreme left-hand limit of movementat which the striker of limit switch LS3 is engaged, and that bottleconveyor 38 is moving to the left to advance a bottle B into thedecorating position. Until the striker of limit switch LS1 is engaged bythe arrival of the bottle at the decorating position, contacts LSla oflimit switch LS1 (FIGURE 6) will remain closed to complete a circuitacross supply lines L1 and L2 to motor M2. When the bottle arrives atthe decorating position, conveyor 38 engages limit switch LS1 andcontacts LSla are opened to stop the bottle conveyor drive motor M2.

When the bottle arrives at the decorating position and engages thestriker of limit switch LS1, it closes a set of normally open contactsLSlb of limit switch LS1 to complete a circuit across supply lines L1and L2 through the now closed contacts LSlb and a set of normally closedcontrol relay contacts Ca to simultaneously energize belt drive motorM1, electric potential sources V1 and V2 and pneumatic motor controlrelay 34R.

Ener-gization of solenoid 34R causes pneumatic motor 34 to retract itspiston, thereby drawing screen 28 to the right as viewed in FIGURE 1. Asthe screen moves to the right, the periphery of bottle B is frictionallyengaged by a portion 52 of screen frame 30 to cause the bottle to rollor rotate about its axis R with a no-sli-p rolling motion as the screenis drawn to the right by the retraction of piston rod 36.

Simultaneously with the movement of screen 28 to the right as viewed inFIGURE 1, belt conveyor drive motor M1 is energized and the upper run 16of the belt also moves to the right, the speed of movement of the beltand screen being identical. Energization of potential sources V1 and V2establish an electric field which extends upwardly from conductivemember 44 to the surface of bottle B, the bottle surface and conductivemember being at opposite electric potentials. Powder supported upon belt10 immediately above conductive member 44 becomes electrically chargedand the electric field impels the charged powder particles upwardlythrough slit 42 and image aperture 32 of screen 28 to the surface ofbottle B. The translatory movement of the screen combined with therolling movement of the bottle relative to the screen advance the bottlesurface into vertical registry with slit 42 at the same peripheral speedas screen 28 is moved horizontally.

The above described action continues until the screen arrives at itsextreme right-hand limit of travel, at which time the striker of limitswitch LS2 is engaged to close its normally opened contacts LSZa.Closure of contacts LSZa completes a circuit through a control relay Cvia a set of normally closed contacts LS3a of limit switch LS3, theselast contacts being closed because the screen is not at its left-handlimit of travel. When control relay C is energized it locks itself in byclosing a set of contacts Cb and simultaneously closes a second set ofnormally open contacts Cc to energize valve control relay 34E to therebycause pneumatic motor 34 to reverse and drive in a direction extendingpiston rod 36 to return the screen toward its left-hand limit of travel.

When control relay C is energized, it opens its normally closed contactsCa, thereby simultaneously de-energizing powder conveyor drive motor M1,voltage sources V1 and V2 and pneumatic motor control relay 34R. Afourth set of control relay contacts Cd are closed to energize bottleconveyor drive motor M2 to convey the decorated bottle away from thedecorating position. Contacts Cd are connected in series with a set ofnormally open contacts LSlc controlled by relay LS1. These lattercontacts are closed when the bottle is in the decorating position andhence mot-or M2 is energized to drive the bottle away from thedecorating position until the striker of limit switch LS1 is disengaged.At this. time, contacts LSlc open, but contacts LSla are now closed tokeep motor M2 energized and the motor continues to drive until the nextsuccessive bottle arrives at the decorating position.

In FIGURE 2 there is disclosed a second embodiment of the invention inwhich a support table designated generally 60 is mounted for horizontalreciprocatory movement. Table 60 is driven in horizontal reciprocatorymovement by mean of a rack 62 on the table which is meshed with one ormore pinions 64, pinions 64 being driven by a suitable reversible drivemotor M3. An electrically conductive plate 66 is mounted upon table 60and surrounded by an upwardly projecting frame 68 of electricalinsulating material which extends entirely around the side edges ofplate 66 to define a recess within which a powder bed 70 is received.Powder is supplied to the bed by means of a hopper such as 72.

A flat plate 74 of electrically non-conductive material having anelongate slit 76 is supported in a stationary position overlying thepowder bed. A stencil screen assembly designated generally 78 ofconstruction identical to that of the FIGURE 1 embodiment is supportedfor horizontal movement across the top of plate 74 and is driven inmovement in the same fashion as the FIGURE 1 embodiment by a pneumaticmotor designated generally 80. A bottle B is conveyed to and fromregistry with slot 76 by a conveyor mechanism 38 identical to thatemployed in the FIGURE 1 embodiment.

As in the FIGURE 1 embodiment, voltage sources V1 and V2 arerespectively connected to plate 66 and to bottle B.

The control system for the embodiment of FIGURE 2 can be precisely thesame as that described in connection with the embodiment of FIGURE 1above. It will be noted that movement of table 60 is simultaneous withthat of the screen assembly 78 and hence the control of reversihle tabledrive motor M3 can be accomplished by the same circuitry employed tocontrol the reversible pneumatic motor 80.

The embodiment of FIGURE 2 differs from that of FIGURE 1 in that insteadof employing narrow elongate conductor 44 of the FIGURE 1 embodiment,plate 66 extends entirely across the bottom of the powder bed. Plate 74is in direct contact with the top of the powder bed and only thoseparticles which are in registry with slot 76 can move. By making plate74 of a material having the same electrically resistive characteristicsas those of the powder, only powder in the region of the slit becomeselectrically charged; powder out of registry with the slit effectivelyacting as a series resistance between plate 66 and plate 74.

In FIGURES 3 and 4, still another embodiment of the invention isdisclosed. In this embodiment, an endless conveyor belt ofsemi-conductive material is operatively tnained around a pair of endrolls 92 and 94, a suitable conveyor drive motor M4 being employed todrive end roll 92 to advance the belt. Powder is dispensed onto theupper run of the belt as from a hopper 96. A stationary plate 98 ofelectrically conductive material is mounted beneath the upper run ofbelt 90 in supporting relationship with the belt. Mounted upon plate 98and extending along each side edge of the conveyor belt are a pair ofupwardly projecting walls 100 of electrical insulating material whichserves to slidably support a plate 102 of electrical insulatingmaterial.

Plate 102 is mounted for sliding movement transversely of the conveyor,as best seen in FIGURE 4, and is driven in transverse reciprocatingmovement by a pneumatic motor assembly designated generally 104. As inthe pre vious cases, plate 102 is pnovided with an elongate slit 106, inthis case the longitudinal extent of silt 106 i parallel to thedirection of movement of conveyor 90. A stencil screen 108 is supportedin a stationary position above plate 102 land a bottle conveyordesignated generally 110 is employed to convey bottles B to and fromoperative registry with the apparatus. As in the case of the previousembodiments, the bottle B is supported for free rotation about itslongitudinal axis by the conveyor 110. Conveyor 110 may be for allpractical purposes identical to the conveyor 38 of the FIGURE 1embodiment, although it is controlled in a manner to be described belowin a slightly different fashion during the decorating cycle. A pad 112is mounted upon the screen assembly to frictionally engage the bottleperiphery to rotate the bottle about its axis as the bottle is carriedtransversely across stencil screen 108.

In the FIGURES 3 and 4 embodiment, the direction of movement of thebottle conveyor is at right angles to the direction of movement ofpowder conveyor 90, as opposed to the parallel relationship of theFIGURE 1 embodiment. The embodiment of FIGURES 3 and 4 further ditfersfrom that of FIGURE 1 in that the screen and powder supply arestationary during the decorating operation while the bottle and slottedplate 102 move in translation during the decorating operation.

An exemplary electrical control circuit for the embodiments of FIGURES 3and 4 is shown in FIGURE 8. Control of pneumatic motor 104 is by aconventional pneumatic system identical to that disclosed in FIGURE 7.In FIGURE 8, the relays 104R and 104E correspond to the pneumaticconnections causing the piston rod of motor 104 to retract (104R) or toextend (104E). Bottle conveyor 110 is driven by a drive motor M5 and thecircuit of FIGURE 8 includes two control relays C1 and C2 respectively.

Referring briefiy to FIGURE 4, two limit switches LS1 and LS2 arerespectively located to be engaged as a bottle arrives at the decoratinglocation and leaves the decorating location, the decorating operationoccurring while the bottle is moving from the position of limit switchLS1 to that of limit switch LS2. Limit switches LS3 and LS4 are locatedto be engaged when slotted plate 102 is at one or the other end of itslimit of movement, limit switch LS4 being engaged by the plate when theplate is ready to begin a decorating stroke, while limit switch LS3 isengaged when the plate reaches the end of its decorating stroke.

As an initial condition, it will be assumed that bottle conveyor 110 ismoving to the left as viewed in FIGURE 4 but has not yet arrived at theposition of limit switch LS1, and that slotted plate 102 is at itsextreme right hand limit of movement as viewed in FIGURE 4, with theplate engaging the striker of limit switch LS4.

With the foregoing conditions, referring to FIGURE 8, control relay C2is energized because with the plate at its ready position, limit switchLS4 is engaged and its normally open contacts LS4a are closed. A set ofnormally closed contacts LS3a controlled by limit switch LS3 are intheir normal closed condition at this time because the striker of limitswitch LS3 is disengaged. Relay C2 is locked in by its controlledlock-in contacts C21; while convey-or drive motor M5 is energized bycontacts C2b closed by the energization of control relay C2.

As conveyor 110 advances the bottle into the decorating region, limitswitch LS1 is engaged and its contacts LSla close to energize controlrelay C1 via contacts LS4c (closed because LS4 is engaged at this timeby the slotted plate) and normally closed contacts LS2a. Control relayC1, when energized, locks in via its lock-in contact Cla which bypasscontacts LSla and LS4a.

Energization of control relay C1 closes its contacts C1b tosimultaneously energize voltage sources V1 and V2 and to energize relay104E to establish the pneumatic connections to motor 104 to cause themotor to drive in a direction extending its piston rod, thereby 8 movingslotted plate 102 to the left as viewed in FIG- URE 4.

The speed of movement of slotted plate 102 and its initial point ofstarting are regulated in accordance with the movement of the bottle Bupon its conveyor so that slot 106 stays in vertical alignment with theaxis of rotation of the bottle B and the plate and bottle move in unisonfrom right to left as viewed in FIG- URE 4. Throughout this time,voltage sources V1 and V2 are energized and powder is electricallytransferred upwardly through slot 106 and stencil screen 108 to thebottle surface. The bottle is rotated during this movement by virtue ofits peripheral contact with the rolling rail 112 (FIGURE 3).

Simultaneous movement of the bottle and slotted plate 102 continue untilthe bottle conveyor contacts limit switch LS2. Contacting of limitswitch LS2 opens the normally closed contacts LSZa, therebyde-energizing relay C1 and by the consequent opening of its contacts C1bde-energizing the two voltage sources and motor control relay 104E.Slightly after the engagement of limit switch LS2 by the bottleconveyor, limit switch LS3 is engaged by plate 102 when the platereaches the conclusion of its leftward stroke. Engagement of limitswitch LS3 opens its contacts LS3a thereby de-energiZing control relayC2 to open contact C2b. However, conveyor motor M5 remains energized andkeeps driving via the normally closed bypass contacts LSlb which areclosed because the striker of limit switch LS1 is now disengaged by theconveyor.

De-energization of relay C2 closes its normally closed contacts C20 toenergize conveyor drive motor M4 and pneumatic motor control relay 104R,energization of this latter relay conditioning motor 104 to drive in adirection retracting its piston rod. Relay 104R and conveyor drive motorM4 remain energized until plate 102 is restored to its ready position atwhich time contacts C2c open by the energization of relay C2 by closureof contacts LS4a upon the engagement of limit switch LS4 by plate 102.

It will be noted that relay C2 does not become energized until the plate102 is restored to its ready position. In the event a subsequent bottleB is conveyed by conveyor 110 to the decorating position before plate102 is restored to its ready position, the conveyor drive motor M5 willbe stopped by the opening of contacts LSlb when the conveyor arrives atthe beginning of the decorating region. When the plate returns to itsready position, limit switch LS4 is engaged to close contacts LS4a,thereby energizing relay C2 to close contact C2b to start the bottleconveyor motor M5. Contacts LS4a prevent the starting of a decoratingcycle unless a bottle and the plate are in their ready positions.

In FIGURE 5, still another form of the invention is disclosed. TheFIGURE 5 embodiment is quite similar to the FIGURE 1 embodiment with theexception that an endless belt screen is employed in place of thereciprocating screen of the FIGURE 1 embodiment. In FIGURE 5, an endlessconveyor belt is operatively trained about a pair of end rolls 122 and124, end roll 122 being driven as by a motor M6. A powder hopper 126 isemployed to dispense powder 128 in a layer of uniform thickness upon theupper run of belt 120. A plate 130 having an elongate slit 132therethrough is supported in fixed position above the upper run of belt120 and an elongate electrically conductive member 134 extendstransversely beneath the upper run of belt 120 in vertical registry withslit 132. A bottle conveyor similar to conveyor 38 of FIGURE 1 anddesignated generally 136 carries bottles B in a direction parallel toslit 132 and perpendicular to the direction of movement of conveyor belt120. As in the previous cases, the conveyor 1336 supports the bottle forrotation about its longitudinal axis.

A stencil screen in the form of an endless belt 138 is operativelytrained around a series of tour guide rollers 140, at least one of theguide rollers being operatively coupled to a suitable drive motor suchas M7. As in the previous cases, electric potential sources V1 and V2are respectively connected to the conductive member 134 and to thebottle, the stencil screen being connected to the electrical ground.

In the FIGURE 5 embodiment, a motor M8 is employed to drive the bottleconveyor, and as in the BIG- URE 1 embodiment, a limit switch LS1 islocated to sense the arrival of a bottle in operative registry with theapparatus. Projecting tongues or cars such as 142 are mounted upon thestencil screen so that the arrival of the screen at its ready positionrelative to the decorating apparatus can be sensed when an car 142engages the striker of a limit switch LS2. A third limit switch, LS3, islocated somewhat in advance of limit switch LS2 for purposes which willbecome apparent in the description of the control circuit.

The electrical control circuit :for the FIGURE 5 embodiment is disclosedin FIGURE 9. Assuming a bottle is located in operative registry with theapparatus, limit switch LS1 will be engaged and its contacts LSla willbe opened, thereby opening the circuit to conveyor drive motor M8.Contacts LSlb will be closed, and assuming the screen is in its readyposition with LS2 engaged by an ear 142, contacts LSZa will also beclosed, thereby completing a circuit through normal closed contacts LS3aof limit switch LS3 to energize a control relay C1. Contacts Cla and 01bare closed by the energization of relay C1 thereby energizing voltagesources V1 and V2 and powder conveyor drive motor M6 via contacts Claand energizing screen drive motor M7 via contacts Clb. Relay C1 islocked in by contacts Clc which bypass contacts LSlb and LSZa.

The above conditions remain until the screen is advanced to a positionwhere the striker of limit switch LS3 is engaged by one of the ears 142on the screen. This engagement occurs after the decorating process hasbeen completed, but before the screen is advanced a complete step to itsnext ready position. Engagement of limit switch LS3 opens contacts LS3athereby de-energizing relay C1, opening contacts Cla to de-energize thepotential sources V1 and V2 and the powder conveyor drive motor M6.

Engagement of limit switch LS3 also closes its normally open contactsLS3 to energize a second control relay C2 via normal closed contactsLS2c of the now disengaged limit switch LS2. Energization of relay C2closes its contacts C2a to energize motor M8 to drive the bottle awayfrom the decorating position, at which time contacts LSla close tomaintain motor M8 driving upon the later opening of contacts C2a. RelayC2 is locked in by contacts C2c which bypass contacts LS3b. Screen drivemotor M7 is energized by the closure of contacts C2b and drives untilthe screen reaches its ready position, at which time contacts LS2c areopened, de-energizing relay C2 which opens contacts C2c and C2b to stopscreen drive motor M7 and transfer control of bottle conveyeor motor M8to contacts LSla.

Relay C2 is energized during the period necessary for the screen car 142to advance from engagement with limit switch LS3 into engagement withlimit switch LS2. This relatively short time interval is sufl'icient toener gize bottle conveyor motor M8 long enough via contacts C2a to drivethe conveyor clear of limit switch LS1, thereby causing contacts LSla toclose before contacts C211 open.

For purposes of illustration, the invention has been described in termsof decorating a cylindrical bottle surface, and is believed apparentthat tapered or conical surfaces can equally well be decorated byappropriate modification of the conveyor support yokes. In the casewhere the bottle cross section is non-circular, as for exampleelliptical cross section, the support yoke may be modified toreciprocate vertically during the rotation of the bottle to maintainthat portion of the bottle surface registered with the slit at aconstant distance above the stencil throughout the rotary movement ofthe bottle.

While various embodiments of the invention have been described indetail, it will be apparent to those skilled in the art that thedisclosed embodiments may be modified, therefore, the foregoingdescription is to be considered exemplary rather than limiting, and thetrue scope of the invention is that defined in the following claims.

I claim:

1. The method of applying an image-shaped layer of printing powderparticles to an article surface which is a surface of revolutioncomprising the steps of supporting the article for rotation about theaxis of its surface of revolution with the axis located above ahorizontal stencil screen having an image defining aperturetherethrough, positioning a source of printing powder particles beneathsaid screen in vertical registry therewith, positioning a horizontallydisposed plate having an elongate slit therethrough between said sourceand said screen with said slit extending parallel to said surface and invertical registry with said, axis, said elongate slit being relativelynarrow with respect to said article and having a length at least equalto the length of said image along said axis, applying electricpotentials of opposite polarity to said source and said article toelectrically charge and attract particles from said source successivelythrough said slit and the aperture of said screen to the surface of saidarticle, moving said article and said screen horizontally relative toeach other in a direction normal to said axis and simultaneouslyrotating said article about said axis to cause the article surface toroll laterally relative to said screen entirely across said imageaperture while said electric potentials are applied to said source andsaid screen, and maintaining said slit in vertical registry with saidaxis during relative movement between said article and screen.

2. The method as defined in claim 1 wherein the step of positioning saidsource of printing powder particles comprises the steps of depositingprinting powder particles in a layer of uniform thickness upon ahorizontal support surface, advancing the support surface with the layerof particles thereon into vertical registry with said stencil screen,and maintaining the screen and support surface against horizontalmovement relative to each other during the period of relative movementbetween said screen and said axis.

3. The method as defined in claim 2 wherein the step of applyingelectric potentials of opposite polarity to said source and said articlecomprises the steps of supporting the layer of printing powder particlesabove an electrically conductive plate, and connecting said plate to asource of electric potential while maintaining said plate in verticalregistry with said screen.

4. The method as defined in claim 2 wherein the step of applyingelectric potentials of opposite polarity to said source and said articlecomprises the steps of supporting the layer of printing powder particlesupon an electrically semi-conductive member, locating a relativelynarrow elongate electrically conductive member in a horizontal positionbeneath said semi-conductive member in vertical registry with said slit,connecting said electrically conductive member to a source of electricpotential, and maintaining said conductive member in vertical registrywith said slit and said axis during the period of relative motionbetween said screen and said axis.

5. Apparatus for electrically applying an image-shaped layer of printingpowder particles to an article surface which is a surface of revolutioncomprising a flat stencil screen means having an image defining aperturetherethrough, a fiat plate having an elongate slit therethroughunderlying said screen means, said elongate slit being relatively narrowwith respect to said article and having a length at least equal to thelength of said image along the axis of revolution of said surface,movable powder bed support means for positioning a bed of printingpowder particles beneath said plate in vertical registry with saidscreen means, movable article support means supporting an article forrotation about the axis of its surface with the article above saidscreen means and with its axis located in vertical registry with saidslit in said plate and with the surface of the article closest to theplate extending in parallel relationship thereto, support meanssupporting said screen means for horizontal movement relative to saidplate and supported article transversely of the longitudinal extent ofsaid slit to pass said slit beneath said aperture from a location at oneside of said aperture to a location at the other side of said aperture,means operable upon relative movement between said screen means and saidplate and article support for rotating the article about its axis tocause the article surface to roll laterally relative to said screenentirely across said image aperture with said article support meansmaintaining the surface of the article closest to said screen paralleltherewith and maintaining the article axis and slit in said fixedvertical registry with each other, electric potential means operablewhen actuated to electrically charge and impel particles in said bedupwardly through said slit and said image aperture to said articlesurface, and control means operable to actuate said potential means andto simultaneously shift said plate and said screen relative to eachother to pass said slit beneath said aperture from one side of saidaperture to the other with said axis in fixed vertical registry withsaid slit during the relative movement between said plate and saidscreen.

6. Apparatus as defined in claim wherein said screen means comprises anendless belt operatively trained about a series of guide rollers, saidbelt having a plurality of uniformly spaced image defining aperturestherethrough, and means for driving said belt in uniform increments ofmovement to successively advance the apertures into vertical registrywith said bed.

7. Apparatus as defined in claim 5 wherein said plate is mounted in afixed position, and means operable by said control means for moving saidpowder bed support means horizontally during relative movement betweensaid plate and said screen means to maintain said powder bed againsthorizontal movement relative to said screen means.

8. Apparatus as defined in claim 7 wherein said screen means comprises aframe supporting a horizontal stencil screen, and means operable by saidcontrol means for driving said screen frame in horizontal reciprocatorymovement relative to said plate.

9. Apparatus as defined in claim 7 wherein said powder support meanscomprises an endless belt conveyor having a horizontally extending rundisposed beneath said plate, and means overlying said run of saidconveyor belt for depositing printing powder particles in a layer ofuniform thickness upon said run in advance of said plate.

10. Apparatus as defined in claim 7 wherein said powder bed supportmeans comprises a reciprocatory plate movable into and out of registrywith said stencil screen, and powder supply means for depositingprinting powder particles upon said plate in a layer of uniformthickness when said plate is out of registry with said screen.

11. Apparatus for electrically applying an image shaped layer ofprinting powder particles to a cylindrical article surface comprising anendless belt conveyor having a horizontally extending upper run, meansoperable to drive said conveyor belt to advance the upper run in a firstdirection, means adjacent the upstream end of said upper run fordepositing printing powder particles thereon in a layer of uniformthickness, a flat plate overlying said upper run and having an elongateslot therethrough extending transversely across said upper run, astencil screen having an image defining aperture therethrough overlyingsaid flat plate, means for moving said stencil screen horizontally abovesaid slot between a first position wherein the aperture of said screenis located at one side of said slot and a second position wherein saidaperture is located at the opposite side of said slot, article supportmeans for supporting an article for rotation about the axis of itscylindrical surface and for positioning said article above said screenwith its axis extending horizontally in vertical registry with saidslot, electric potential means operable when actuated to electricallycharge powder particles in said bed and to impel said particles upwardlythrough said slot and said aperture to the article surface, meansresponsive to the location of an article with its axis in verticalregistry with said slot for actuating said potential means and forsimultaneously actuating said screen driving means to drive said screenbetween said first and second positions, and means on said screenengageable with said article surface to rotate said article about itsaxis by horizontal movement of said screen.

References Cited UNITED STATES PATENTS 2,484,671 10/ 1949 Bauman.3,273,496 9/1966 Melmon. 3,306,193 2/1967 Rarey et al. 3,307,477 3/1967Booher 10l -1l4 2,940,864 6/1960 Watson. 3,081,698 3/1963 Childress etal. 101l22 3,251,706 5/ 1966 Walkup.

EDGAR S. BURR, Primary Examiner US. Cl. X.R.

